This is cross-posted from the Den of Shadows message board.
As to writer's block in general, I tend to get stuck for a couple reasons.
1. I took the easy way out while writing something. Meaning rather than writing what would be better for the characters and plot, I wrote what was easier or what came to me first without giving it some extra thought. Then I usually can't figure out where to go from there, so I "delete" (meaning I just copy it into a new document) what I wrote (sometimes it'll be a paragraph and sometimes it'll be an entire chapter) and start over. I get stuck this way the most during the actual writing process.
2. This is also during the writing process, where I can look at my outline and know what I need to write, I just have no idea how to go about doing it. (This is probably my problem with my new chapter 1.) This block is the hardest to fix since it pretty much forces me to become a better writer than I am now, or I have to rework my plot to make a different scene fit.
3. I have no idea where the story is going or needs to go. This can happen during either the outlining stage or while I'm writing, since I tend to write a lot of things that weren't included in my outline (especially in the middle of the book). To get past this, I usually need to do a lot of brainstorming either by writing down all the ideas I can think of myself, or by talking to my husband.